1. Field of the Invention
This invention relates to the field of fluid purification, and to the purification of inert, non-reactive and reactive fluids. Furthermore, the invention relates to methods and materials for selectively removing trace amounts of impurities from inert, non-reactive and reactive fluids.
2. Description of the Prior Art
The provision of high purity fluid streams is critically important in a wide variety of industrial and research applications. The rapid expansion of vapor-phase processing techniques, e.g., chemical vapor deposition, in the semiconductor industry has been associated with the deployment and use of manufacturing equipment that is totally reliant on the delivery of high purity process fluids at the point of use in the semiconductor manufacturing facility.
Considering the impurities which are present in fluid streams involved in semiconductor manufacturing, it is to be noted that the growth of high quality thin film electronic and optoelectronic cells by chemical vapor deposition or other vapor-based techniques is inhibited by a variety of low-level process impurities. These impurities can cause defects that reduce yields by increasing the number of rejects, which can be very expensive. These impurities may be particulate or chemical contaminants.
Chemical impurities may originate in the production of the source fluid itself, as well as in its subsequent packaging, shipment, storage, and handling. Although source fluid manufacturers typically provide analyses of source gas materials delivered to the semiconductor manufacturing facility, the purity of the fluids may change because of leakage into or outgassing of the containers, e.g., gas cylinders, in which gases are packaged. Impurity contamination may also result from improper fluid containers changes, leaks into downstream processing equipment, or outgassing of such downstream equipment.
In semiconductor manufacturing processes, for example, removal of impurities helps to ensure the production of high-quality, high-performance semiconductor chips. Such impurities, when introduced onto the semiconductor chip during its manufacture, tend to render the chip deficient or even useless for its intended purpose. Thus, a growing number of industries are now requiring fluids having impurity concentrations that do not exceed about 10 parts-per-billion (ppb) levels.
For example, in the manufacture of III-V semiconductor devices using metal-organic chemical vapor deposition (MOCVD), Group IIIA organometallic source gases, such as tri-methyl aluminum, tri-methyl indium and tri-methyl gallium may be purified by fractional distillation and/or sublimation to remove impurities. These organometallic compounds are highly reactive with oxygen, and form oxygenated impurities that can significantly degrade the performance of III-V semiconductor devices.
There remains a need in the art for a reagent that removes contaminants such as oxygen and water from inert, non-reactive and reactive fluids. Further, there remains a need for purification methods and apparatuses that provide relatively fast equilibration between fluid and purifier to ensure adequate concentrations of purified fluid can be provided at the point of use. Also, a need exists for purifier materials that remove oxygen and oxygenated species and other impurities from inert, non-reactive and reactive fluids without concurrently emitting contaminants such as moisture into the purified fluid stream.